Bleaching process.



WALTHER MATHESIUS AND MORITZ FREIBERGER, OF CHARLOTTENBURG, GERMANY.

BLEACHING- PROCESS.

No Drawing. Original application filed. December 28, 1911, Serial No.668,315.

Specification of Letters Patent.

Patented May 13,1913.

Divided and this application filed July 23, 1912. Serial No. 711,111.

To all whom it may concern:

Be it known that we, WVALTHER MATHE- s1Us, a subject of the King ofPrussia, and Monrrz FREIBERGER, a subject of the Emperor ofAustria-Hungary, bot-h residing at Charlottenburg, near Berlin, Germany,have jointly invented a new and Improved Bleaching Process, of which thefollowing is a specification.

This invention relates to an improved process for bleaching cotton goodsin rope form and constitutes subject matter divided out from ourconcurrent United States patent application Serial No. 668315 filedDecember 28th, 1911.

The essential feature of the present invention is that the fabric iskept in continuous forward motion and subjected to alkaline bleaching,washing and acid treatments in immediate succession.

It has heretofore been proposed to carry out successive alkaline andacid bleaching processes, but such processes have hitherto not beensuccessful either because it was not deemed advisable to depart from theold principle of storing the fabric in a suitable vessel after passingit through the bleaching solution, leaving it for some time in thestorage vessel to the action of the bleaching solution, it havinghitherto been assumed that if this is not done, the fabric would not besufiiciently bleached, or because it had been deemed advisable to raisethe strength of the bleaching solution and then thoroughly wash it inhot water before treating it with acid to neutralize the bleachingaction. The latter process, however, damages the fabric withoutappreciably improving the bleaching.

According to the present invention the fabric is moved slowly butcontinuously through the vessels containing the liquids for treatment,such vessels being preferably of the type described in the specificationof our aforesaid concurrent patent application,

the fabric requiring from to minutes to pass through the alkaline andacid bleaching vessels. The fabric is first of all subjected to theaction of a warm alkaline bleaching liquid, such as h aerate.

lime, in the first vessel, w ich decompb s'es the greater part of thecoloring substances remaining in the fabric from the scouring tank. Thefabric is moved slowly and continuously through the alkaline bleachingliquid for a period of about 10 to 25 minutes and immediately uponleaving the bleaching liquid is passed through a rinsing tank containinga weak-hypochlorite of lime solution, so that a certain definite amountof bleaching liquid remains on the fabric after it leaves the rinsingtank. The fabric is thereupon immediately passed through another vesselcontaining an acid solution, the fabric being moved slowly andcontinuously through this vessel for a period of 10 to 25 minutes andupon leaving the acid containing vessel, the fabric may be finallywashed. In order to accelerate the action of the liquids, the latter maybe slightly heated, but it is essential that the liquids be not heatedto such a temperature as would cause partial or entire decomposition. Itis therefore impossible to inject steam into the bleaching liquids or toheat the liquids by means of steam-heated tubes as has heretofore beenproposed. It is essential that heating tubes or other suitable heatingsurfaces be employed which are not heated to an essentially highertemperature than that to which the bleaching liquids are to be raised,and for this purpose a fiuid such as warm water of the requisitetemperature is therefore circulated through the heating tubes or thelike.

It will be noted in the foregoing process that the fabric is not leftfor some time to the action of the bleaching liquid in the first tanknor is it thoroughly washed before being treated with acid. By using awarm bleaching liquid in the first tank it is possible to considerablyaccelerate the passage of the fabric through this tank and to carry outthe removal of the larger quantity of the coloring matters to such anextent that the acid bleaching action can be effected when only a smallquantity of the alkaline bleaching solution remains in the fabric. Thebleaching process is thus divided into two steps, the first step, thealkaline bleaching, being intentionally not carried out to the extenthitherto usual, so that only those coloring matters are removed whichare easily capable of being oxidized without only subjected for a shorttime thereto. Moreover, not only are those substances removed which areonly capable of being decomposed by the acid, but also the 'rest ofthose substances which are indeed capable of being decomposed by thealkaline solution but which would require such intensive action on thepart of the alkaline solution that oxycellulose would be formed. Theimproved process moreover results in a saving of time and enables a pureand durable white to be obtained.

WVe claim 1. The method of bleaching cotton goods in rope form whichconsists in continuously moving the fabric forward and effecting inimmediate succession partial alkaline bleacl1- ing in a warm alkalinebleaching solution, partial rinsing in a rinsing liquid and completionof the bleaching in an acid solution.

2. The method of bleaching cotton goods in rope form which consists incontinuously moving the fabric forward and effecting in immediatesuccession partial alkaline bleaching in a warm alkaline bleachingsolution, partial rinsing in a rinsing liquid and completion of thebleaching in a warm acid solu tion.

3. The method of bleaching cotton goods in rope form which consists incontinuously but slowly moving the fabric through a warm alkalinebleaching solution for a period of from 10 to 25 minutes, so as toeffect partial alkaline bleaching thereby, immediately thereuponpartially rinsing the fabric so as to leave a little alkaline bleachingsolution thereon, and immediately thereupon and in continued slowforward movement passing the fabric through an acid solution for aperiod of from 10 to 25 minutes to complete the bleaching.

4. The method of bleaching cotton goods in rope form which consists incontinuously moving the fabric forward and effecting in immediatesuccession, partial alkaline bleaching in an alkaline bleachingsolution, partial rinsing in a rinsing liquid and completion of thebleaching in an acid solution, and simultaneously heating said solutionsby means not heated to an essentially higher temperature than that towhich the solutions are to be raised.

5. The method of bleaching cotton goods in rope form which consists incontinuously moving the fabric forward and effecting, in immediatesuccession, partial alkaline bleaching in an alkaline bleachingsolution, partial rinsing in a rinsing liquid and completion of thebleaching in an acid solution, and simultaneously heating said solutionsby passing a fluid of a temperature not essentially higher than that towhich the solutions are to be raised, through said solutions withoutdirect contact therewith.

In testimony whereof we have hereunto affixed our signatures in presenceof two witnesses.

VVALTHER MATHESIUS. MORITZ FREIBERGER. \Vitnesses:

\VoLDEMAR HAUPT, HENRY HASPER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

